1. Field of the Invention
The present invention relates to a method for manufacturing a circuit device, and more particularly relates to a method for manufacturing a circuit device including a plurality of wiring layers laminated with an insulating layer interposed therebetween.
2. Description of the Related Art
With reference to FIG. 25, a description will be given of a configuration of a conventional circuit device 100. This technology is described for instance in Japanese Patent Application Publication No. 2001-339151 (FIG. 1 in p. 1). FIG. 25 is a cross-sectional view of the conventional circuit device.
In the conventional circuit device 100, a first conductive pattern 102A is formed on the surface of a supporting substrate 101, and a second conductive pattern 102B is formed on the rear surface of the supporting substrate 101. In addition, a semiconductor element 104 and a chip element 106 are fixed on the first conductive pattern 102A. The first conductive pattern 102A and the semiconductor element 104 are electrically connected to each other with thin metal wires 105. Moreover, the first conductive pattern 102A and the elements mounted on the first conductive pattern 102A are sealed with a sealing resin 103. As a method for sealing with the sealing resin 103, there are injection molding using a thermoplastic resin, and transfer molding using a thermosetting resin.
Moreover, the first conductive pattern 102A formed on the surface of the supporting substrate 101 and the second conductive pattern 102B formed on the rear surface of the supporting substrate 101 are connected to each other through a contact hole 108. The contact hole 108 is formed by burying a conductor in a hole formed in a manner to penetrate the supporting substrate 101.
Furthermore, with reference to FIGS. 26A and 26B, a description will be given of a configuration of a conventional hybrid integrated circuit device 200. This technology is described for instance in Japanese Patent Application Publication No. Hei 6 (1994)-177295. FIG. 26A is a perspective view of the hybrid integrated circuit device 200, and FIG. 26B is a cross-sectional view along the line X-X′ in FIG. 26A.
The conventional hybrid integrated circuit device 200 includes a rectangular substrate 206, and an insulating layer 207 provided on the surface of the substrate 206. On this insulating layer 207, a wiring layer 208 is patterned. Furthermore, a circuit element 204 is fixed on the wiring layer 208, and the circuit element 204 and the wiring layer 208 are electrically connected to each other by use of thin metal wires 205. Leads 201 electrically connected to the wiring layer 208 are extended to the outside. Moreover, the entire hybrid integrated circuit device 200 is sealed with a sealing resin 202. As a method for sealing the device with the sealing resin 202, there are injection molding using a thermoplastic resin, and transfer molding using a thermosetting resin.
However, in the circuit device 100 described above, a substrate made of an organic material such as an epoxy resin is used as the supporting substrate 101. The reason why such a substrate made of the organic material is used is because of consideration for workability in forming the contact hole 108. However, since an organic substrate such as a glass epoxy substrate has a low thermal conductivity, there is a problem that heat generated from embedded elements cannot be efficiently released to the outside. Moreover, if a resin having a large amount of inorganic fillers mixed therein is used as a material of the supporting substrate 101 in order to improve heat release properties of the supporting substrate 101, there arises a problem that formation of the contact hole 108 becomes difficult.
Furthermore, in the hybrid integrated circuit device 200 described above, formation of a single layer wiring leads to a problem that limits a size of an electric circuit that can be integrated. As one of methods for solving this problem, there is a method for forming a multilayer structure of wirings laminated with an insulating layer interposed therebetween. The laminated wiring layers are electrically connected to each other through a connection part formed in a manner to penetrate the insulating layer. Moreover, in consideration for heat release properties, the insulating layer has inorganic fillers mixed therein. However, if a large amount of inorganic fillers are mixed in the insulating layer in order to improve the heat release properties, there arises a problem that formation of the connection part which penetrates the insulating layer becomes difficult. Specifically, it is difficult to form a multilayer wiring structure which secures the heat release properties.